Optical apparatus with optical system having long optical path

Abstract

An appartus, such as a binocular telescope, with an optical system which includes a long optical path. The binocular telescope includes a first objective lens, a second objective lens, a first prism, a second prism, and a group of eye piece lenses. A body of the second prism has an outer surface on which a film made of aluminum is deposited. A light which passes through the first objective lens is firstly reflected by an outer surface, or an exposed side, of the deposited film, and then reflected by an inner surface, or a side contacting the body of the second prism, of the film after the light passes through the second objective lens, the first prism and the second prism. The light reflected by the inner surface of the film is projected outside through the second prism and the eye piece lenses. The single deposited film serves as a pair of reflection elements within the optical system, so that the long optical path is secured therein.

What id claimed is:  
     
       1. An optical apparatus having a prism and at least one optical element, the prism comprising: 
       a first surface through which an incident light passes into a body of the prism;  
       a second surface having an inner side by which the incident light is reflected into a reflection light within the body; and  
       a third surface through which the reflection light is projected outside the body,  
       wherein the prism is arranged such that an outer side of the second surface reflects light, that is travelling inside the optical apparatus and is incident upon the outer side of the second surface, outwardly from the prism to the at least one optical element.  
     
     
       2. An optical apparatus as claimed in  claim 1 , wherein the second surface is provided with a metal deposited film which is deposited on the body of the prism. 
     
     
       3. An optical apparatus as claimed in  claim 1 , wherein the prism is one of a plurality of components which constitute a finder optical system. 
     
     
       4. An optical apparatus as claimed in  claim 1 , wherein the outer side of the second surface is employed as a reflection surface which is one of a plurality of components constituting an active measuring system for automatic focusing. 
     
     
       5. An optical apparatus as claimed in  claim 1 , wherein the outer side of the second surface is employed as a reflection surface which is one of a plurality of components constituting a photometering system for automatic exposure. 
     
     
       6. An optical apparatus as claimed in  claim 1 , wherein both the inner side and the outer side of the second surface are employed as a pair of reflection surfaces within a same optical system. 
     
     
       7. An optical apparatus according to  claim 1 , wherein the optical element to which light from the outer side of the surface of the prism is reflected is an element in an image observing system for observing an image. 
     
     
       8. An optical apparatus according to  claim 1 , wherein the optical element to which light from the outer side of the second surface of the prism is reflected is a sensor. 
     
     
       9. An optical apparatus according to  claim 1 , wherein the prism reflects light, that was once reflected by the inner side of the second surface of the prism, with the outer side of the second surface of the prism, and the prism reflects light, that was once reflected by the outer side of the second surface of the prism, with the inner side of the second surface of the prism. 
     
     
       10. An optical apparatus with an optical element, the optical element comprising: 
       a first surface having a first inner side and a first outer side; and  
       a second surface having a second inner side and a second outer side,  
       wherein an incident light which passes into a body of the optical element is reflected by the first inner side of the first surface and the second inner side of the second surface into a reflection light which is projected outside the body, and  
       wherein each of the first outer side of the first surface and the second outer side of the second surface reflects light, that is travelling inside the optical apparatus and is incident on the outer side of the first surface and the outer side of the second surface, outwardly from the optical element.  
     
     
       11. An optical apparatus as claimed in  claim 10 , wherein each of the first surface and the second surface is provided with a metal deposited film which is deposited on the body of the optical element. 
     
     
       12. An optical apparatus as claimed in  claim 10 , wherein the optical element is one of a plurality of components which constitute a finder optical system. 
     
     
       13. An optical apparatus as claimed in  claim 10 , wherein at least one of the first outer side and the second outer side is employed as a reflection surface which is one of a plurality of components constituting an active measuring system for automatic focusing. 
     
     
       14. An optical apparatus as claimed in  claim 10 , wherein at least one of the first outer side and the second outer side is employed as a reflection surface which is one of a plurality of components constituting a photometering system for automatic exposure. 
     
     
       15. An optical apparatus as claimed in  claim 10 , wherein the first inner side, the second inner side, and at least one of the first outer side and the second outer side, are employed as reflection surfaces within a same optical system. 
     
     
       16. An optical apparatus according to  claim 10 , further comprising a second optical element, wherein light that is reflected by at least one of the first outer side of the first surface and the second outer side of the second surface is directed toward the second optical element. 
     
     
       17. An optical apparatus having a prism and at least one optical element, the prism comprising: 
       a first surface through which an incident light passes into a body of the prism; and  
       a second surface having an inner side and an outer side;  
       wherein the incident light which passes through said first surface is reflected into a reflection light within the body by the inner side of said second surface, and  
       wherein the outer side of said second surface reflects light, that is travelling inside the optical apparatus and is incident on the outer side of said second surface, outwardly from the prism to the at least one optical element.  
     
     
       18. An optical apparatus according to  claim 17 , wherein the optical element to which light from the outer side of the surface of the prism is reflected is an element in an image observing system for observing an image. 
     
     
       19. An optical apparatus according to  claim 17 , wherein the optical element to which light from the outer side of the second surface of the prism is reflected is a sensor. 
     
     
       20. An optical apparatus according to  claim 17 , wherein the prism reflects light, that was once reflected by the inner side of the second surface of the prism, with the outer side of the second surface of the prism, and the prism reflects light, that was once reflected by the outer side of the second surface of the prism, with the inner side of the second surface of the prism.